OPERATOR’S MANUAL 1/2 in. HAMMER DRILL VARIABLE SPEED DOUBLE INSULATED D551H Your hammer drill has been engineered and manufactured to Ryobi’s high standard for dependability, ease of operation, and operator safety. When properly cared for, it will give you years of rugged, trouble-free performance. WARNING: To reduce the risk of injury, the user must read and understand the operator’s manual before using this product. Thank you for buying a Ryobi product.
TABLE OF CONTENTS n Introduction ..................................................................................................................................................................... 2 �n General Safety Rules .................................................................................................................................................... 3-4 �n Specific Safety Rules..............................................................................................................
GENERAL SAFETY RULES n Keep your work area clean and well lit. Cluttered benches and dark areas invite accidents. n Do not operate power tools in explosive atmospheres, such as in the presence of flammable liquids, gases, or dust. Power tools create sparks which may ignite the dust or fumes. n Keep bystanders, children, and visitors away while operating a power tool. Distractions can cause you to lose control. n Avoid accidental starting. Be sure switch is off before plugging in.
GENERAL SAFETY RULES SERVICE n When servicing a tool, use only identical replacement parts. Follow instructions in the Maintenance section of this manual. Use of unauthorized parts or failure to follow Maintenance Instructions may create a risk of shock or injury. n Tool service must be performed only by qualified repair personnel. Service or maintenance performed by unqualified personnel may result in a risk of injury.
SYMBOLS Some of the following symbols may be used on this tool. Please study them and learn their meaning. Proper interpretation of these symbols will allow you to operate the tool better and safer.
SYMBOLS The following signal words and meanings are intended to explain the levels of risk associated with this product. SYMBOL SIGNAL MEANING DANGER: Indicates an imminently hazardous situation, which, if not avoided, will result in death or serious injury. WARNING: Indicates a potentially hazardous situation, which, if not avoided, could result in death or serious injury. CAUTION: Indicates a potentially hazardous situation, which, if not avoided, may result in minor or moderate injury.
ELECTRICAL DOUBLE INSULATION EXTENSION CORDS Double insulation is a concept in safety in electric power tools, which eliminates the need for the usual threewire grounded power cord. All exposed metal parts are isolated from the internal metal motor components with protecting insulation. Double insulated tools do not need to be grounded. When using a power tool at a considerable distance from a power source, be sure to use an extension cord that has the capacity to handle the current the tool will draw.
FEATURES PRODUCT SPECIFICATIONS Chuck Capacity..............................................................................................................................................5/64 in. - 1/2 in. Hammer Speed ................................................................................................................................... Low (0 - 16,000 BPM*) High (0 - 48,000 BPM*) No Load Speed .....................................................................................................
FEATURES KNOW YOUR HAMMER DRILL LOCK-ON BUTTON See Figure 1. Before attempting to use this product, familiarize yourself with all operating features and safety rules. The hammer drill contains a lock-on feature that allows you to lock the drill on when you operate it continuously for extended periods of time. AUXILIARY HANDLE ASSEMBLY MODE SELECTOR An auxiliary handle assembly is installed on the hammer drill. For ease of operation, you may use the handle with either your left hand or your right hand.
ASSEMBLY UNPACKING WARNING: This product has been shipped completely assembled. If any parts are missing do not operate this tool until the missing parts are replaced. Failure to heed this warning could result in possible serious personal injury. n Carefully remove the tool and any accessories from the box. Make sure that all items listed in the packing list are included. n Inspect the tool carefully to make sure no breakage or damage occurred during shipping.
OPERATION WARNING: CHUCK JAWS Always unplug the drill before inserting or removing bits or adjusting the auxiliary handle assembly or depth gauge rod. Failure to unplug the tool could result in accidental starting causing possible serious injury. INSERTING BITS See Figure 2. n Unplug the hammer drill. DRILL BIT n Position the chuck jaws so that the opening is slightly larger than the drill bit you intend to use. NOTE: To open the chuck jaws, turn the chuck collar counterclockwise.
OPERATION ADJUSTING THE DEPTH GAUGE ROD See Figure 5. n Unplug the hammer drill. n Loosen the handle assembly by turning the handle counterclockwise. n Adjust the depth gauge rod so that the drill bit extends beyond the end of the rod to the required drilling depth. n Tighten handle assembly by turning handle clockwise. ADJUST DEPTH GAUGE ROD ADJUSTING THE DRILL MODE TO TIGHTEN See Figure 6.
OPERATION TURNING THE HAMMER DRILL ON/OFF See Figure 8. To turn the hammer drill on and off. n To turn the drill on: depress the switch trigger. n To turn the drill off: release the switch trigger. CHANGING THE ROTATION See Figure 9. The direction of the chuck is controlled by the lever located above the switch trigger. NOTE: The design of the switch will not permit changing the direction of rotation while the drill is running.
OPERATION DRILLING See Figure 11. n Depress and release the switch trigger to make sure the drill is in the OFF position before connecting it to a power supply. n Check the rotation lever for the correct setting. Refer to “CHANGING THE ROTATION” earlier in this manual. n Secure the material to be drilled in a vise or with clamps to keep it from turning as the drill bit rotates. n Plug the hammer drill into a power supply. n Hold the drill firmly and place the bit at the point to be drilled.
MAINTENANCE Electric tools used on fiberglass material, wallboard, spackling compounds, or plaster are subject to accelerated wear and possible premature failure because the fiberglass chips and grindings are highly abrasive to bearings, brushes, commutators, etc. Consequently, we do not recommended using this tool for extended work on these types of materials. However, if you do work with any of these materials, it is extremely important to clean the tool using compressed air.
OPERATOR’S MANUAL 1/2 in. HAMMER DRILL VARIABLE SPEED DOUBLE INSULATED D551H • SERVICE Now that you have purchased your tool, should a need ever exist for repair parts or service, simply contact your nearest Ryobi Authorized Service Center. Be sure to provide all pertinent facts when you call or visit. Please call 1-800-525-2579 for your nearest Ryobi Authorized Service Center. You can also check our web site at www.ryobitools.com for a complete list of Authorized Service Centers. • MODEL NO.